This work investigates the rational basis for altruism, arguing that the capacity to act in the interest of others is a requirement of practical reason rather than merely a matter of sentiment. Thomas Nagel, a prominent philosopher, utilizes a rigorous analytical framework to demonstrate that if one accepts the objective reality of one's own needs, one must logically accept the objective reality of the needs of others. By examining the structure of practical reasoning, he posits that moral motivation is inherent in the rational agent's understanding of their place in the world.

This text is widely regarded as a foundational contribution to contemporary moral philosophy and is frequently studied in advanced ethics courses. Scholars often note the high degree of technical precision in Nagel's arguments, which demand careful attention from the reader.